Fig. 4
From: Top-down feedback controls spatial summation and response amplitude in primate visual cortex
Feedback controls the amplitude of V1 responses. a, b Spatial-summation curves for two example V1 cells measured without laser (black) and with (green) laser stimulation at two different intensities (solid green: 9 mW/mm2; dashed green 43 mW/mm2). Other conventions are as in Fig. 2a. c Response amplitude (here defined as mean response over the entire spatial summation curve) for each cell at low and high laser intensity (n = 14). d sRF diameter for each cell at low and high laser intensity. Black and red dots in c–e indicate cells showing significant (T-test, p < 0.05) and non-significant change in response amplitude, respectively. Arrows in c–d: means. Dashed line in c–d: unity line. e sRF size change (ratio of diameter at low to high laser) vs. response change (ratio of response amplitude at low to high laser). Shaded area indicates cells for which sRF size increased and response amplitude decreased with increasing laser intensity (and vice versa). Dashed line: regression line
